Ethical Nutrients Bone Builder MCHC with Magnesium, Boron & Vitamin D is a comprehensive bone support formula that features the same calcium-rich MCHC found in original Bone Builder, but with added bone-nourishing nutrients. This MCHC is cryogenically processed to preserve the protein matrix and organic factors. It features a 2:1 ratio of calcium to magnesium. Boron is a trace mineral that may support healthy calcium balance. Vitamin D is an essential nutrient that helps maintain healthy bones.